Due to the high rotational speed, high temperature, and high reliability requirements of commercial aviation engines, the lubrication design of hot-end cylindrical roller bearings has become critical. To reveal the lubricant oil flow characteristics inside the bearing cavity under different rotational speeds and clearances, this study aims to optimize and enhance the oil spray lubrication effect of the bearings. A high-precision hydrodynamic model of cylindrical roller bearing was constructed based on the fluid dynamics theory. Moreover, by defining the rotational coordinate system, the motion relations of the bearing components were described. Subsequently, the oil-air flow in the bearing cavity was numerically solved using the Volume of Fluid (VOF) model and Semi-Implicit Method for Pressure Linked Equations (SIMPLE) to obtain the distribution of the oil-air two phases. The macroscopic motion characteristics under different working conditions were studied by varying the rotational speed, pocket clearance, and guide clearance. The lubrication performance of the bearings was evaluated based on the pressure field, velocity field, and oil phase distribution, highlighting the influence of rotational speed and clearance on the cylindrical roller bearings, ultimately optimizing the lubrication design. The findings offer crucial theoretical guidance for the lubrication instruction of bearings, which is vital for ensuring their high reliability.